Organic electroluminescent materials and devices

ABSTRACT

A metal iridium complexes, devices containing the same, and formulations including the same described. The complexes can have the formula Ir(L1)n(L2)3-n, whereinthe first ligand L1 has Formula I,the second ligand L2 has Formula II,L1 is different from L2; R1 is a partially or fully deuterated group consisting of alkyl and cycloalkyl; R2 represents mono, di, tri substitutions or no substitution; R3, R4, and R5 each represent mono, di, tri, tetra substitutions or no substitution; R2 and R3 are each independently selected from the group consisting of hydrogen, deuterium, alkyl, cycloalkyl, and combinations thereof; R4 and R5 are each independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; and n is 1 or 2. Homoleptic, tris-iridium complex including deuterated alkyl groups are also described.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Non-Provisional applicationSer. No. 13/798,972, filed Mar. 13, 2013, which claims priority to U.S.Provisional Application Ser. No. 61/767,508, filed Feb. 21, 2013, theentire content of which is incorporated herein by reference.

PARTIES TO A JOINT RESEARCH AGREEMENT

The claimed invention was made by, on behalf of, and/or in connectionwith one or more of the following parties to a joint universitycorporation research agreement: Regents of the University of Michigan,Princeton University, University of Southern California, and theUniversal Display Corporation. The agreement was in effect on and beforethe date the claimed invention was made, and the claimed invention wasmade as a result of activities undertaken within the scope of theagreement.

FIELD OF THE INVENTION

The present invention relates to compounds for use as emitters anddevices, such as organic light emitting diodes, including the same.

BACKGROUND

Opto-electronic devices that make use of organic materials are becomingincreasingly desirable for a number of reasons. Many of the materialsused to make such devices are relatively inexpensive, so organicopto-electronic devices have the potential for cost advantages overinorganic devices. In addition, the inherent properties of organicmaterials, such as their flexibility, may make them well suited forparticular applications such as fabrication on a flexible substrate.Examples of organic opto-electronic devices include organic lightemitting devices (OLEDs), organic phototransistors, organic photovoltaiccells, and organic photodetectors. For OLEDs, the organic materials mayhave performance advantages over conventional materials. For example,the wavelength at which an organic emissive layer emits light maygenerally be readily tuned with appropriate dopants.

OLEDs make use of thin organic films that emit light when voltage isapplied across the device. OLEDs are becoming an increasinglyinteresting technology for use in applications such as flat paneldisplays, illumination, and backlighting. Several OLED materials andconfigurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and5,707,745, which are incorporated herein by reference in their entirety.

One application for phosphorescent emissive molecules is a full colordisplay. Industry standards for such a display call for pixels adaptedto emit particular colors, referred to as “saturated” colors. Inparticular, these standards call for saturated red, green, and bluepixels. Color may be measured using CIE coordinates, which are wellknown to the art.

One example of a green emissive molecule is tris(2-phenylpyridine)iridium, denoted Ir(ppy)₃, which has the following structure:

In this, and later figures herein, we depict the dative bond fromnitrogen to metal (here, Ir) as a straight line.

As used herein, the term “organic” includes polymeric materials as wellas small molecule organic materials that may be used to fabricateorganic opto-electronic devices. “Small molecule” refers to any organicmaterial that is not a polymer, and “small molecules” may actually bequite large. Small molecules may include repeat units in somecircumstances. For example, using a long chain alkyl group as asubstituent does not remove a molecule from the “small molecule” class.Small molecules may also be incorporated into polymers, for example as apendent group on a polymer backbone or as a part of the backbone. Smallmolecules may also serve as the core moiety of a dendrimer, whichconsists of a series of chemical shells built on the core moiety. Thecore moiety of a dendrimer may be a fluorescent or phosphorescent smallmolecule emitter. A dendrimer may be a “small molecule,” and it isbelieved that all dendrimers currently used in the field of OLEDs aresmall molecules.

As used herein, “top” means furthest away from the substrate, while“bottom” means closest to the substrate. Where a first layer isdescribed as “disposed over” a second layer, the first layer is disposedfurther away from substrate. There may be other layers between the firstand second layer, unless it is specified that the first layer is “incontact with” the second layer. For example, a cathode may be describedas “disposed over” an anode, even though there are various organiclayers in between.

As used herein, “solution processible” means capable of being dissolved,dispersed, or transported in and/or deposited from a liquid medium,either in solution or suspension form.

A ligand may be referred to as “photoactive” when it is believed thatthe ligand directly contributes to the photoactive properties of anemissive material. A ligand may be referred to as “ancillary” when it isbelieved that the ligand does not contribute to the photoactiveproperties of an emissive material, although an ancillary ligand mayalter the properties of a photoactive ligand.

As used herein, and as would be generally understood by one skilled inthe art, a first “Highest Occupied Molecular Orbital” (HOMO) or “LowestUnoccupied Molecular Orbital” (LUMO) energy level is “greater than” or“higher than” a second HOMO or LUMO energy level if the first energylevel is closer to the vacuum energy level. Since ionization potentials(IP) are measured as a negative energy relative to a vacuum level, ahigher HOMO energy level corresponds to an IP having a smaller absolutevalue (an IP that is less negative). Similarly, a higher LUMO energylevel corresponds to an electron affinity (EA) having a smaller absolutevalue (an EA that is less negative). On a conventional energy leveldiagram, with the vacuum level at the top, the LUMO energy level of amaterial is higher than the HOMO energy level of the same material. A“higher” HOMO or LUMO energy level appears closer to the top of such adiagram than a “lower” HOMO or LUMO energy level.

As used herein, and as would be generally understood by one skilled inthe art, a first work function is “greater than” or “higher than” asecond work function if the first work function has a higher absolutevalue. Because work functions are generally measured as negative numbersrelative to vacuum level, this means that a “higher” work function ismore negative. On a conventional energy level diagram, with the vacuumlevel at the top, a “higher” work function is illustrated as furtheraway from the vacuum level in the downward direction. Thus, thedefinitions of HOMO and LUMO energy levels follow a different conventionthan work functions.

More details on OLEDs, and the definitions described above, can be foundin U.S. Pat. No. 7,279,704, which is incorporated herein by reference inits entirety.

SUMMARY OF THE INVENTION

According to an embodiment, a heteroleptic iridium compound isdescribed. The heteroleptic iridium compound can have the formulaIr(L¹)_(n)(L²)_(3-n): wherein the ligand L¹ is a first ligand havingFormula I,

andthe ligand L² is a second ligand having Formula II,

wherein L¹ is different from L²; R¹ is a partially or fully deuteratedgroup consisting of alkyl and cycloalkyl; R² represents mono, di, trisubstitutions or no substitution; R³, R⁴ and R⁵ each represent mono, di,tri, tetra substitutions or no substitution. R² and R³ are eachindependently selected from the group consisting of hydrogen, deuterium,alkyl, cycloalkyl, and combinations thereof. R⁴ and R⁵ are eachindependently selected from the group consisting of hydrogen, deuterium,halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy,amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl,heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof; andwherein n is 1 or 2.

According to another embodiment, a first device comprising a firstorganic light emitting device is also provided. The first device caninclude an anode, a cathode, and an organic layer, disposed between theanode and the cathode. The organic layer can include a compound havingthe formula Ir(L¹)_(n)(L²)_(3-n). The first device can be a consumerproduct, an organic light-emitting device, and/or a lighting panel. Inyet another embodiment the organic layer can include a homoleptic,tris-iridium complex including deuterated alkyl groups.

According to still another embodiment, a formulation that includes acompound having the formula Ir(L¹)_(n)(L²)_(3-n) is provided.

According to another embodiment, homoleptic, tris-iridium complexesincluding deuterated alkyl groups are provided.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detaileddescription when read in conjunction with the accompanying drawing. Itis emphasized that, according to common practice, the various featuresof the drawing are not necessarily to scale. On the contrary, thedimensions of the various features are arbitrarily expanded or reducedfor clarity. Like numerals denote like features throughout thespecification and drawings.

FIG. 1 shows an organic light emitting device.

FIG. 2 shows an inverted organic light emitting device that does nothave a separate electron transport layer.

FIG. 3 shows Formula I as disclosed herein.

FIG. 4 shows Formula II as disclosed herein.

DETAILED DESCRIPTION

Generally, an OLED comprises at least one organic layer disposed betweenand electrically connected to an anode and a cathode. When a current isapplied, the anode injects holes and the cathode injects electrons intothe organic layer(s). The injected holes and electrons each migratetoward the oppositely charged electrode. When an electron and holelocalize on the same molecule, an “exciton,” which is a localizedelectron-hole pair having an excited energy state, is formed. Light isemitted when the exciton relaxes via a photoemissive mechanism. In somecases, the exciton may be localized on an excimer or an exciplex.Non-radiative mechanisms, such as thermal relaxation, may also occur,but are generally considered undesirable.

The initial OLEDs used emissive molecules that emitted light from theirsinglet states (“fluorescence”) as disclosed, for example, in U.S. Pat.No. 4,769,292, which is incorporated by reference in its entirety.Fluorescent emission generally occurs in a time frame of less than 10nanoseconds.

More recently, OLEDs having emissive materials that emit light fromtriplet states (“phosphorescence”) have been demonstrated. Baldo et al.,“Highly Efficient Phosphorescent Emission from OrganicElectroluminescent Devices,” Nature, vol. 395, 151-154, 1998;(“Baldo-I”) and Baldo et al., “Very high-efficiency green organiclight-emitting devices based on electrophosphorescence,” Appl. Phys.Lett., vol. 75, No. 3, 4-6 (1999) (“Baldo-II”), which are incorporatedby reference in their entireties. Phosphorescence is described in moredetail in U.S. Pat. No. 7,279,704 at cols. 5-6, which are incorporatedby reference.

FIG. 1 shows an organic light emitting device 100. The figures are notnecessarily drawn to scale. Device 100 may include a substrate 110, ananode 115, a hole injection layer 120, a hole transport layer 125, anelectron blocking layer 130, an emissive layer 135, a hole blockinglayer 140, an electron transport layer 145, an electron injection layer150, a protective layer 155, a cathode 160, and a barrier layer 170.Cathode 160 is a compound cathode having a first conductive layer 162and a second conductive layer 164. Device 100 may be fabricated bydepositing the layers described, in order. The properties and functionsof these various layers, as well as example materials, are described inmore detail in U.S. Pat. No. 7,279,704 at cols. 6-10, which areincorporated by reference.

More examples for each of these layers are available. For example, aflexible and transparent substrate-anode combination is disclosed inU.S. Pat. No. 5,844,363, which is incorporated by reference in itsentirety. An example of a p-doped hole transport layer is m-MTDATA dopedwith F4-TCNQ at a molar ratio of 50:1, as disclosed in U.S. PatentApplication Publication No. 2003/0230980, which is incorporated byreference in its entirety. Examples of emissive and host materials aredisclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which isincorporated by reference in its entirety. An example of an n-dopedelectron transport layer is BPhen doped with Li at a molar ratio of 1:1,as disclosed in U.S. Patent Application Publication No. 2003/0230980,which is incorporated by reference in its entirety. U.S. Pat. Nos.5,703,436 and 5,707,745, which are incorporated by reference in theirentireties, disclose examples of cathodes including compound cathodeshaving a thin layer of metal such as Mg:Ag with an overlyingtransparent, electrically-conductive, sputter-deposited ITO layer. Thetheory and use of blocking layers is described in more detail in U.S.Pat. No. 6,097,147 and U.S. Patent Application Publication No.2003/0230980, which are incorporated by reference in their entireties.Examples of injection layers are provided in U.S. Patent ApplicationPublication No. 2004/0174116, which is incorporated by reference in itsentirety. A description of protective layers may be found in U.S. PatentApplication Publication No. 2004/0174116, which is incorporated byreference in its entirety.

FIG. 2 shows an inverted OLED 200. The device includes a substrate 210,a cathode 215, an emissive layer 220, a hole transport layer 225, and ananode 230. Device 200 may be fabricated by depositing the layersdescribed, in order. Because the most common OLED configuration has acathode disposed over the anode, and device 200 has cathode 215 disposedunder anode 230, device 200 may be referred to as an “inverted” OLED.Materials similar to those described with respect to device 100 may beused in the corresponding layers of device 200. FIG. 2 provides oneexample of how some layers may be omitted from the structure of device100.

The simple layered structure illustrated in FIGS. 1 and 2 is provided byway of non-limiting example, and it is understood that embodiments ofthe invention may be used in connection with a wide variety of otherstructures. The specific materials and structures described areexemplary in nature, and other materials and structures may be used.Functional OLEDs may be achieved by combining the various layersdescribed in different ways, or layers may be omitted entirely, based ondesign, performance, and cost factors. Other layers not specificallydescribed may also be included. Materials other than those specificallydescribed may be used. Although many of the examples provided hereindescribe various layers as comprising a single material, it isunderstood that combinations of materials, such as a mixture of host anddopant, or more generally a mixture, may be used. Also, the layers mayhave various sublayers. The names given to the various layers herein arenot intended to be strictly limiting. For example, in device 200, holetransport layer 225 transports holes and injects holes into emissivelayer 220, and may be described as a hole transport layer or a holeinjection layer. In one embodiment, an OLED may be described as havingan “organic layer” disposed between a cathode and an anode. This organiclayer may comprise a single layer, or may further comprise multiplelayers of different organic materials as described, for example, withrespect to FIGS. 1 and 2 .

Structures and materials not specifically described may also be used,such as OLEDs comprised of polymeric materials (PLEDs) such as disclosedin U.S. Pat. No. 5,247,190 to Friend et al., which is incorporated byreference in its entirety. By way of further example, OLEDs having asingle organic layer may be used. OLEDs may be stacked, for example asdescribed in U.S. Pat. No. 5,707,745 to Forrest et al, which isincorporated by reference in its entirety. The OLED structure maydeviate from the simple layered structure illustrated in FIGS. 1 and 2 .For example, the substrate may include an angled reflective surface toimprove out-coupling, such as a mesa structure as described in U.S. Pat.No. 6,091,195 to Forrest et al., and/or a pit structure as described inU.S. Pat. No. 5,834,893 to Bulovic et al., which are incorporated byreference in their entireties.

Unless otherwise specified, any of the layers of the various embodimentsmay be deposited by any suitable method. For the organic layers,preferred methods include thermal evaporation, ink-jet, such asdescribed in U.S. Pat. Nos. 6,013,982 and 6,087,196, which areincorporated by reference in their entireties, organic vapor phasedeposition (OVPD), such as described in U.S. Pat. No. 6,337,102 toForrest et al., which is incorporated by reference in its entirety, anddeposition by organic vapor jet printing (OVJP), such as described inU.S. Pat. No. 7,431,968, which is incorporated by reference in itsentirety. Other suitable deposition methods include spin coating andother solution based processes. Solution based processes are preferablycarried out in nitrogen or an inert atmosphere. For the other layers,preferred methods include thermal evaporation. Preferred patterningmethods include deposition through a mask, cold welding such asdescribed in U.S. Pat. Nos. 6,294,398 and 6,468,819, which areincorporated by reference in their entireties, and patterning associatedwith some of the deposition methods such as ink jet and OVJD. Othermethods may also be used. The materials to be deposited may be modifiedto make them compatible with a particular deposition method. Forexample, substituents such as alkyl and aryl groups, branched orunbranched, and preferably containing at least 3 carbons, may be used insmall molecules to enhance their ability to undergo solution processing.Substituents having 20 carbons or more may be used, and 3-20 carbons isa preferred range. Materials with asymmetric structures may have bettersolution processibility than those having symmetric structures, becauseasymmetric materials may have a lower tendency to recrystallize.Dendrimer substituents may be used to enhance the ability of smallmolecules to undergo solution processing.

Devices fabricated in accordance with embodiments of the presentinvention may further optionally comprise a barrier layer. One purposeof the barrier layer is to protect the electrodes and organic layersfrom damaging exposure to harmful species in the environment includingmoisture, vapor and/or gases, etc. The barrier layer may be depositedover, under or next to a substrate, an electrode, or over any otherparts of a device including an edge. The barrier layer may comprise asingle layer, or multiple layers. The barrier layer may be formed byvarious known chemical vapor deposition techniques and may includecompositions having a single phase as well as compositions havingmultiple phases. Any suitable material or combination of materials maybe used for the barrier layer. The barrier layer may incorporate aninorganic or an organic compound or both. The preferred barrier layercomprises a mixture of a polymeric material and a non-polymeric materialas described in U.S. Pat. No. 7,968,146, PCT Pat. Application Nos.PCT/US2007/023098 and PCT/US2009/042829, which are herein incorporatedby reference in their entireties. To be considered a “mixture”, theaforesaid polymeric and non-polymeric materials comprising the barrierlayer should be deposited under the same reaction conditions and/or atthe same time. The weight ratio of polymeric to non-polymeric materialmay be in the range of 95:5 to 5:95. The polymeric material and thenon-polymeric material may be created from the same precursor material.In one example, the mixture of a polymeric material and a non-polymericmaterial consists essentially of polymeric silicon and inorganicsilicon.

Devices fabricated in accordance with embodiments of the invention maybe incorporated into a wide variety of consumer products, including flatpanel displays, computer monitors, medical monitors, televisions,billboards, lights for interior or exterior illumination and/orsignaling, heads up displays, fully transparent displays, flexibledisplays, laser printers, telephones, cell phones, personal digitalassistants (PDAs), laptop computers, digital cameras, camcorders,viewfinders, micro-displays, vehicles, a large area wall, theater orstadium screen, or a sign. Various control mechanisms may be used tocontrol devices fabricated in accordance with the present invention,including passive matrix and active matrix. Many of the devices areintended for use in a temperature range comfortable to humans, such as18 degrees C. to 30 degrees C., and more preferably at room temperature(20-25 degrees C.).

The materials and structures described herein may have applications indevices other than OLEDs. For example, other optoelectronic devices suchas organic solar cells and organic photodetectors may employ thematerials and structures. More generally, organic devices, such asorganic transistors, may employ the materials and structures.

The terms halo, halogen, alkyl, cycloalkyl, alkenyl, alkynyl, arylkyl,heterocyclic group, aryl, alkaryl, aromatic group, and heteroaryl areknown to the art, and are defined in U.S. Pat. No. 7,279,704 at cols.31-32, which are incorporated herein by reference.

As used herein, “substituted” indicates that a substituent other than His bonded to the relevant carbon. Thus, where R² is monosubstituted,then one R² must be other than H. Similarly, where R³ is disubstituted,the two of R³ must be other than H. Similarly, where R² is unsubstitutedR² is hydrogen for all available positions.

According to an embodiment, heteroleptic iridium complexes are provided,which unexpectedly exhibit improved lifetime and make them more suitablefor commercial applications. In particular, the heteroleptic complexescan be based on 2-phenylpyridine ligands that include a deuterated alkylgroup in the 5^(th) position on the pyridine ring (i.e., thepara-position relative to the phenyl group). In addition, a number ofhomoleptic, tris-iridium complexes including deuterated alkyl groupsthat also exhibit unexpectedly improved lifetime were discovered.

According to one embodiment, a heteroleptic iridium compound having theformula Ir(L¹)_(n)(L²)_(3-n) is provided. The first ligand L¹ has astructure according to Formula I:

and the second ligand L² has a structure according to Formula II:

-   -   wherein L¹ is different from L²;    -   wherein R¹ is a partially or fully deuterated group consisting        of alkyl and cycloalkyl;    -   wherein R² represents mono, di, tri substitutions or no        substitution;    -   wherein R³, R⁴, and R⁵ each represent mono, di, tri, tetra        substitutions or no substitution;    -   wherein R² and R³ are each independently selected from the group        consisting of hydrogen, deuterium, alkyl, cycloalkyl, and        combinations thereof;    -   wherein R⁴ and R⁵ are each independently selected from the group        consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl,        heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl,        cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl,        carbonyl, carboxylic acids, ester, nitrile, isonitrile,        sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations        thereof; and wherein n is 1 or 2

In some embodiments, R¹ is a fully deuterated group selected from thegroup consisting of alkyl and cycloalkyl. More particularly, in someembodiments, R¹ is a fully deuterated group selected from the groupconsisting of methyl, ethyl, propyl, 1-methylethyl, butyl,1-methylpropyl, 2-methylpropyl, pentyl, 1-methylbutyl, 2-methylbutyl,3-methylbutyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl,2,2-dimethylpropyl, cyclopentyl, cyclohexyl.

In some more specific embodiments, the first ligand L¹ is selected fromthe group consisting of:

In some embodiments, the second ligand L² is selected from the groupconsisting of:

-   -   wherein R^(A), and R^(C) each represent mono, di, tri, tetra        substitutions or no substitution;    -   wherein R^(B) represents mono, di, tri substitutions or no        substitution; and    -   wherein R^(A), R^(B), and R^(C) are independently selected from        the group consisting of hydrogen, deuterium, methyl, ethyl,        propyl, 1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl,        pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl,        1,1-dimethylpropyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl,        cyclopentyl, cyclohexyl, and combinations thereof.

In some specific embodiments, the compound is selected from the groupconsisting of:

According to another aspect of the present disclosure, a first device isalso provided. The first device includes a first organic light emittingdevice, that includes an anode, a cathode, and an organic layer disposedbetween the anode and the cathode. The organic layer can include acompound having the formula Ir(L¹)_(n)(L²)_(3-n), and any variationsthereof described herein. In some embodiments, the organic layer caninclude a compound of Formula II as described herein, and variationsthereof.

The first device can be one or more of a consumer product, an organiclight-emitting device and a lighting panel. The organic layer can be anemissive layer and the compound can be an emissive dopant in someembodiments, while the compound can be a non-emissive dopant in otherembodiments.

The organic layer can also include a host. In some embodiments, the hostcan include a metal complex. The host can be a triphenylene containingbenzo-fused thiophene or benzo-fused furan. Any substituent in the hostcan be an unfused substituent independently selected from the groupconsisting of C_(n)H_(2n+1), OC_(n)H_(2n+1), OAr₁, N(C_(n)H_(2n+2),N(Ar₁)(Ar₂), CH═CH—C_(n)H_(2n+1), C≡C—C_(n)H_(2n+1), Ar₁, Ar₁—Ar₂,C_(n)H_(2n)—Ar₁, or no substitution. In the preceding substituents n canrange from 1 to 10; and Ar₁ and Ar₂ can be independently selected fromthe group consisting of benzene, biphenyl, naphthalene, triphenylene,carbazole, and heteroaromatic analogs thereof.

The host can be a compound selected from the group consisting ofcarbazole, dibenzothiphene, dibenzofuran, dibenzoselenophene,azacarbazole, aza-dibenzothiophene, aza-dibenzofuran, andaza-dibenzoselenophene. The “aza” designation in the fragments describedabove, i.e., aza-dibenzofuran, aza-dibenzothiophene, etc., means thatone or more of the C—H groups in the respective fragment can be replacedby a nitrogen atom, for example, and without any limitation,azatriphenylene encompasses both dibenzo[f,h]quinoxaline anddibenzo[f,h]quinoline. One of ordinary skill in the art can readilyenvision other nitrogen analogs of the aza-derivatives described above,and all such analogs are intended to be encompassed by the terms as setforth herein. The host can include a metal complex. The host can be aspecific compound selected from the group consisting of:

and combinations thereof.

In yet another aspect of the present disclosure, a formulation thatincludes a compound including L₁ coordinated to a metal M as describedherein is described. In some embodiments, the formulation can include acompound having the formula Ir(L¹)_(n)(L²)_(3-n), and any variationsthereof described herein. The formulation can include one or morecomponents selected from the group consisting of a solvent, a host, ahole injection material, hole transport material, an electron transportlayer material (see below).

Another aspect of the present disclosure is drawn to homoleptic,tris-iridium complexes including deuterated alkyl groups. In someembodiments, the tris-iridium complexes can be selected from the groupconsisting of:

According to yet another aspect of the present disclosure, a firstdevice is also provided. The first device includes a first organic lightemitting device, that includes an anode, a cathode, and an organic layerdisposed between the anode and the cathode. The organic layer caninclude a homoleptic, tris-iridium complex. The homoleptic, tris-iridiumcomplex can be selected from the group consisting of:

Combination with Other Materials

The materials described herein as useful for a particular layer in anorganic light emitting device may be used in combination with a widevariety of other materials present in the device. For example, emissivedopants disclosed herein may be used in conjunction with a wide varietyof hosts, transport layers, blocking layers, injection layers,electrodes and other layers that may be present. The materials describedor referred to below are non-limiting examples of materials that may beuseful in combination with the compounds disclosed herein, and one ofskill in the art can readily consult the literature to identify othermaterials that may be useful in combination.

HIL/HTL:

A hole injecting/transporting material to be used in the presentinvention is not particularly limited, and any compound may be used aslong as the compound is typically used as a hole injecting/transportingmaterial. Examples of the material include, but not limit to: aphthalocyanine or porphyrin derivative; an aromatic amine derivative; anindolocarbazole derivative; a polymer containing fluorohydrocarbon; apolymer with conductivity dopants; a conducting polymer, such asPEDOT/PSS; a self-assembly monomer derived from compounds such asphosphonic acid and silane derivatives; a metal oxide derivative, suchas MoO_(x); a p-type semiconducting organic compound, such as1,4,5,8,9,12-Hexaazatriphenylenehexacarbonitrile; a metal complex, and across-linkable compounds.

Examples of aromatic amine derivatives used in HIL or HTL include, butnot limit to the following general structures:

Each of Ar¹ to Ar⁹ is selected from the group consisting aromatichydrocarbon cyclic compounds such as benzene, biphenyl, triphenyl,triphenylene, naphthalene, anthracene, phenalene, phenanthrene,fluorene, pyrene, chrysene, perylene, azulene; group consisting aromaticheterocyclic compounds such as dibenzothiophene, dibenzofuran,dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene,benzoselenophene, carbazole, indolocarbazole, pyridylindole,pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole,oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine,pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine,indole, benzimidazole, indazole, indoxazine, benzoxazole, benzisoxazole,benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline,quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine,phenazine, phenothiazine, phenoxazine, benzofuropyridine,furodipyridine, benzothienopyridine, thienodipyridine,benzoselenophenopyridine, and selenophenodipyridine; and groupconsisting 2 to 10 cyclic structural units which are groups of the sametype or different types selected from the aromatic hydrocarbon cyclicgroup and the aromatic heterocyclic group and are bonded to each otherdirectly or via at least one of oxygen atom, nitrogen atom, sulfur atom,silicon atom, phosphorus atom, boron atom, chain structural unit and thealiphatic cyclic group. Wherein each Ar is further substituted by asubstituent selected from the group consisting of hydrogen, deuterium,halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy,amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl,heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof.

In one aspect, Ar¹ to Ar⁹ is independently selected from the groupconsisting of:

k is an integer from 1 to 20; X¹⁰¹ to X¹⁰⁸ is C (including CH) or N;Z¹⁰¹ is NAr¹, O, or S; Ar¹ has the same group defined above.

Examples of metal complexes used in HIL or HTL include, but not limit tothe following general formula:

Met is a metal, which can have an atomic weight greater than 40;(Y¹⁰¹-Y¹⁰²) is a bidentate ligand, Y¹⁰¹ and Y¹⁰² are independentlyselected from C, N, O, P, and S; L¹⁰¹ is an ancillary ligand; k′ is aninteger value from 1 to the maximum number of ligands that may beattached to the metal; and k′+k″ is the maximum number of ligands thatmay be attached to the metal.

In one aspect, (Y¹⁰¹-Y¹⁰²) is a 2-phenylpyridine derivative. In anotheraspect, (Y¹⁰¹-Y¹⁰²) is a carbene ligand. In another aspect, Met isselected from Ir, Pt, Os, and Zn. In a further aspect, the metal complexhas a smallest oxidation potential in solution vs. Fc⁺/Fc couple lessthan about 0.6 V.

Host:

The light emitting layer of the organic EL device of the presentinvention preferably contains at least a metal complex as light emittingmaterial, and may contain a host material using the metal complex as adopant material. Examples of the host material are not particularlylimited, and any metal complexes or organic compounds may be used aslong as the triplet energy of the host is larger than that of thedopant. While the Table below categorizes host materials as preferredfor devices that emit various colors, any host material may be used withany dopant so long as the triplet criteria is satisfied.

Examples of metal complexes used as host are preferred to have thefollowing general formula:

Met is a metal; (Y¹⁰³-Y¹⁰⁴) is a bidentate ligand, Y¹⁰³ and Y¹⁰⁴ areindependently selected from C, N, O, P, and S; L¹⁰¹ is an anotherligand; k′ is an integer value from 1 to the maximum number of ligandsthat may be attached to the metal; and k′+k″ is the maximum number ofligands that may be attached to the metal.

In one aspect, the metal complexes are:

(O—N) is a bidentate ligand, having metal coordinated to atoms O and N.In another aspect, Met is selected from Ir and Pt. In a further aspect,(Y¹⁰³-Y¹⁰⁴) is a carbene ligand.

Examples of organic compounds used as host are selected from the groupconsisting aromatic hydrocarbon cyclic compounds such as benzene,biphenyl, triphenyl, triphenylene, naphthalene, anthracene, phenalene,phenanthrene, fluorene, pyrene, chrysene, perylene, azulene; groupconsisting aromatic heterocyclic compounds such as dibenzothiophene,dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran,benzothiophene, benzoselenophene, carbazole, indolocarbazole,pyridylindole, pyrrolodipyridine, pyrazole, imidazole, triazole,oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole,pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine,oxathiazine, oxadiazine, indole, benzimidazole, indazole, indoxazine,benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline,cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine,pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine,benzofuropyridine, furodipyridine, benzothienopyridine,thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine;and group consisting 2 to 10 cyclic structural units which are groups ofthe same type or different types selected from the aromatic hydrocarboncyclic group and the aromatic heterocyclic group and are bonded to eachother directly or via at least one of oxygen atom, nitrogen atom, sulfuratom, silicon atom, phosphorus atom, boron atom, chain structural unitand the aliphatic cyclic group. Wherein each group is furthersubstituted by a substituent selected from the group consisting ofhydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl,alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl,alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester,nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, andcombinations thereof.

In one aspect, host compound contains at least one of the followinggroups in the molecule:

R¹⁰¹ to R¹⁰⁷ is independently selected from the group consisting ofhydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl,alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl,alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester,nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, andcombinations thereof, when it is aryl or heteroaryl, it has the similardefinition as Ar's mentioned above.

k is an integer from 0 to 20 or 1 to 20; k′″ is an integer from 0 to 20.X¹⁰¹ to X¹⁰⁸ is selected from C (including CH) or N. Z¹⁰¹ and Z¹⁰² isselected from NR¹⁰¹, O, or S.

HBL:

A hole blocking layer (HBL) may be used to reduce the number of holesand/or excitons that leave the emissive layer. The presence of such ablocking layer in a device may result in substantially higherefficiencies as compared to a similar device lacking a blocking layer.Also, a blocking layer may be used to confine emission to a desiredregion of an OLED.

In one aspect, compound used in HBL contains the same molecule or thesame functional groups used as host described above.

In another aspect, compound used in HBL contains at least one of thefollowing groups in the molecule:

k is an integer from 1 to 20; L¹⁰¹ is an another ligand, k′ is aninteger from 1 to 3.

ETL:

Electron transport layer (ETL) may include a material capable oftransporting electrons. Electron transport layer may be intrinsic(undoped), or doped. Doping may be used to enhance conductivity.Examples of the ETL material are not particularly limited, and any metalcomplexes or organic compounds may be used as long as they are typicallyused to transport electrons.

In one aspect, compound used in ETL contains at least one of thefollowing groups in the molecule:

R¹⁰¹ is selected from the group consisting of hydrogen, deuterium,halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy,amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl,heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof, when it is aryl or heteroaryl, it has the similar definition asAr's mentioned above.

Ar¹ to Ar² has the similar definition as Ar's mentioned above. k is aninteger from 1 to 20. X¹⁰¹ to X¹⁰⁸ is selected from C (including CH) orN.

In another aspect, the metal complexes used in ETL contains, but notlimit to the following general formula:

(O—N) or (N—N) is a bidentate ligand, having metal coordinated to atomsO, N or N, N; L¹⁰¹ is another ligand; k′ is an integer value from 1 tothe maximum number of ligands that may be attached to the metal.

In any above-mentioned compounds used in each layer of the OLED device,the hydrogen atoms can be partially or fully deuterated. Thus, anyspecifically listed substituent, such as, without limitation, methyl,phenyl, pyridyl, etc. encompasses undeuterated, partially deuterated,and fully deuterated versions thereof. Similarly, classes ofsubstituents such as, without limitation, alkyl, aryl, cycloalkyl,heteroaryl, etc. also encompass undeuterated, partially deuterated, andfully deuterated versions thereof.

In addition to and/or in combination with the materials disclosedherein, many hole injection materials, hole transporting materials, hostmaterials, dopant materials, exciton/hole blocking layer materials,electron transporting and electron injecting materials may be used in anOLED. Non-limiting examples of the materials that may be used in an OLEDin combination with materials disclosed herein are listed in Table 1below. Table 1 lists non-limiting classes of materials, non-limitingexamples of compounds for each class, and references that disclose thematerials.

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EXPERIMENTAL Synthesis of Compound 2

Synthesis of Iridium Dimer.

To a 500 mL round bottom flask was added iridium chloride hydrate (5.16g, 14.65 mmol), 5-(Methyl-d3)-2-phenylpyridine (5.55 g, 32.2 mmol), 120mL 2-ethoxyethanol, and 40 mL water. Nitrogen was bubbled into themixture, which was then heated at 130° C. overnight under nitrogen.

After being heated for 2 days, the reaction mixture was cooled to roomtemperature. A yellow solid was filtered off and washed with methanoland dried to obtain iridium chloro-bridged dimer (7.24 g, 87%).

Synthesis of Iridium (III) Triflate Intermediate.

To a 1 L round bottom flask was added the iridium chloro-bridged dimer(7.24 g, 6.35 mmol) and 600 mL dichloromethane. To this solution asolution of silver triflate (3.43 g, 13.33 mmol) in 100 mL methanol wasadded. An additional 100 mL of dichloromethane was added and thereaction allowed proceeding overnight at room temperature undernitrogen.

The reaction mixture was filtered through Celite® and the Celite® washedwith dichloromethane. The filtrate was evaporated leaving a green solidproduct, Iridium(III) triflate complex (8.7 g, 92%).

Synthesis of Compound 2.

To a 500 mL round bottom flask was added the Iridium(III) triflatecomplex (8.7 g, 11.63 mmol), 4-(Methyl-d3)-2,5-diphenylpyridine (8.67 g,34.9 mmol), 160 mL ethanol, and 160 mL methanol. The reaction mixturewas heated at 105° C. overnight under nitrogen.

Celite® (27 g) was added to the reaction mixture and stirred. Themixture was poured onto a silica gel plug. The silica gel plug waswashed with ethanol and hexane and then the product eluted withdichloromethane. The crude product was purified by column chromatographyto give 4.48 g (49%) of desired product.

Synthesis of Compound 10

Synthesis of Compound 10.

To a 2 L 3-neck round bottom flask was added the Iridium(III) triflatecomplex from the Compound 2 synthesis (above)(23.545 g, 31.5 mmol),2,4-diphenylpyridine (21.85 g, 94 mmol), 450 mL ethanol, and 450 mLmethanol. The reaction mixture was heated to reflux overnight at 105° C.under nitrogen.

The reaction mixture was cooled to room temperature. A solid settled atthe bottom and most of the dark colored liquid was decanted off. Ethanoland Celite® was added and the mixture was stirred and poured on top of asilica gel plug. The plug was washed with ethanol and hexane. Theproduct was eluted with dichloromethane. The crude was purified bycolumn chromatography to give 4.16 g (18%) desired product.

Synthesis of Compound 212

Synthesis of Compound 212.

To a 200 mL round bottom flask was added the Iridium(III) triflatecomplex from the Compound 2 synthesis (1.56 g, 1.73 mmol),5-methyl-d3-2-phenylpyridine (0.896 g, 5.20 mmol), 20 mL ethanol, and 20mL methanol. The reaction mixture was heated at 105° C. overnight undernitrogen.

Celite® was added to the reaction mixture and stirred. The Celite®mixture was added to a Celite® plug and the Celite® was washed withmethanol. The Celite® was washed with dichloromethane to recoverproduct. The product was further purified by column chromatography togive desired product (0.64 g, 43%).

Synthesis of Compound T1

Synthesis of Compound T1.

To a 500 mL round bottom flask was added the Iridium(III) triflatecomplex from the Compound 2 synthesis (6.0 g, 6.67 mmol),4-(Methyl-d3)-2,5-diphenylpyridine (4.97 g, 20.0 mmol), 100 mL ethanol,and 100 mL methanol. The reaction mixture was heated at 105° C.overnight under nitrogen.

Celite® (18 g) was added to the reaction mixture and stirred. TheCelite® mixture was added to a Celite® plug. The Celite® was washed withmethanol and hexane and then dichloromethane to collect product. Thesolid was purified by column chromatography eluting with 40 to 100%dichloromethane/hexane (4.39 g, 70%).

Synthesis of Compound 54 Synthesis of 5-bromo-4-methyl-2-phenylpyridine

A mixture of 2,5-dibromo-4-methylpyridine (20.55 g, 82 mmol),phenylboronic acid (10.49 g, 86 mmol), and potassium carbonate (16.98 g,123 mmol) in 150 mL of DME and 75 mL of H₂O was bubbled with N₂ for 20min. Pd(PPh₃)₄ (0.946 g, 0.819 mmol) was then added, and the mixture washeated to reflux under N₂ for 24 h.

After normal work up, the crude product was purified by column using 2%ethyl acetate in hexanes as solvent to give5-bromo-4-methyl-2-phenylpyridine (14 g, 56.4 mmol, 68.9% yield).

Synthesis of 2-phenyl-4-methyl-5-methyl-d3-pyridine

5-bromo-4-methyl-2-phenylpyridine (9.5 g, 38.3 mmol) was dissolved in100 mL of THF under nitrogen. The solution was cooled to −78° C.Butyllithium (2.5 M, 15.32 ml, 38.3 mmol) was added to the solution in adropwise manner.

The color turned to orange and a precipitate formed. The reactionmixture was kept at the temperature for 0.5 h. Iodomethane-d3 (8.33 g,57.4 mmol) was then added. The reaction was warmed to room temperatureovernight. Water was then added to the reaction. The mixture wasextracted with ethyl acetate, washed with brine, and dried over MgSO₄.The solvent was then evaporated. The crude was purified by column using5% to 10% ethyl acetate and hexanes as solvent to give 4.1 g (58% yield)of product.

Synthesis of Iridium Complex Dimer.

Iridium chloride (4.96 g, 14.06 mmol) and2-phenyl-4-methyl-5-methyl-d3-pyridine (5.5 g, 29.5 mmol) were mixed in80 mL of 2-ethoxyethanol and 27 mL of water.

The mixture was purged with nitrogen for 20 min and then heated toreflux for 60 h. After cooling, the solid was filtered and washed withmethanol and hexanes and dried to give an iridium complex dimer (7.5 g,6.27 mmol, 89% yield).

Synthesis of Iridium-Triflate Intermediate.

The iridium-complex dimer (7.5 g, 6.27 mmol) was mixed in 200 mL ofdichloromethane. Silver triflate (3.38 g, 13.16 mmol) was dissolved in50 mL of methanol and then added to the dimer mixture.

The solution was stirred for 3 h. The reaction mixture was filteredthrough a Celite® pad. The solvent was evaporated to give theiridium-triflate intermediate shown above (9.5 g, 12.24 mmol, 98%yield).

Synthesis of Compound 54.

The iridium-triflate intermediate (2.3 g, 2.96 mmol) and2,4-diphenylpyridine (2.74 g, 11.86 mmol) were mixed in 50 mL of ethanoland 50 mL of methanol.

The mixture was heated to 65 degrees (oil bath temperature) for 3 days.Celite® (2 g) was added to the reaction and the reaction was filteredthrough a Celite® plug. The product was washed with ethanol and hexanes.The solid was then dissolved with DCM. The solid was run through asilica gel plug to give 2 g of Compound 54.

Synthesis of Compound T14 Synthesis of 2,5-diphenyl-d5-4-ethylpyridine

2,5-diphenyl-4-d3-methyl pyridine (5.0 g, 20.13 mmol) was dissolved in100 ml THF and cooled to <−60° C. using a dry ice/acetone bath. A 2.0 Msolution of lithium diisopropyl amide (25.2 ml, 50.3 mmol) was added inportions via syringe to give a white suspension.

The reaction was warmed to room temperature. After 45 minutes, the darkred solution was cooled in a wet ice/acetone bath <0° C. Methyliodide-d3 (19.08 ml, 201 mmol) was added to the reaction. The reactionwas stirred overnight. GC/MS indicated the reaction was complete thenext morning. The reaction was quenched with 7 ml deuterated water. Thecrude was purified by column chromatography to give 4.43 g (83% yield)of desired product.

Synthesis of Compound T14.

The iridium triflate intermediate from the synthesis of Compound 54(2.93 g, 3.14 mmol), above, and 2,5-diphenyl-4-d5-ethyl pyridine (2.493g, 9.43 mmol) were dissolved in 70 ml.

The reaction was heated to reflux overnight. The solid was filteredthrough a Celite® pad, then dissolved with dichloromethane. The crudewas purified by column chromatography using hexanes and dichloromethaneas solvent to give 1.7 g of desired product.

Device Examples

All example devices were fabricated by high vacuum (<10⁻⁷ Torr) thermalevaporation. The anode electrode was 1200 Å of indium tin oxide (ITO).The cathode consisted of 10 Å of LiF followed by 1,000 Å of Al. Alldevices were encapsulated with a glass lid sealed with an epoxy resin ina nitrogen glove box (<1 ppm of H₂O and O₂) immediately afterfabrication. A moisture getter was incorporated inside the package.

The organic stack of the device examples consisted of sequentially, fromthe ITO surface, 100 Å of Compound A or B as the hole injection layer(HIL), 300 Å of 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (α-NPD)as the hole transporting layer (HTL), 300 Å of the inventive compoundsdoped with Compound C as host, with 8-10 wt. % of the iridiumphosphorescent compound as the emissive layer (EML), 50 or 100 Å ofCompound C as a blocking layer (BL), 400 or 450 Å of Alq(tris-8-hydroxyquinoline aluminum) as the ETL. The comparative Exampleswere fabricated similarly to the Device Examples except that Compound Bwas used as the emitter in the EML.

The device results and data are summarized in Tables 1 and 2 from thosedevices. As used herein, NPD, Alq, Compound B and Compound C have thefollowing structures:

The structures are summarized in Table 1, while the test results aresummarized in Tables 2, 3 and 4.

TABLE 1 device Structures of Inventive Compound and Comparative CompoundEML HIL HTL (300 Å, Example (100 Å) (300 Å) doping %) BL ETL Example 1Compound B NPD Compound 2 Compound C Alq (10%)  (50 Å) (450 Å) Example 2Compound B NPD Compound 212 Compound C Alq (10%)  (50 Å) (450 Å) Example3 Compound B NPD Compound 10 Compound C Alq (10%)  (50 Å) (450 Å)Example 4 Compound B NPD Compound 54 Compound C Alq (10%)  (50 Å) (450Å) Example 5 Compound B NPD Compound T1 Compound C Alq  (8%)  (50 Å)(450Å) Example 6 Compound B NPD Compound T14 Compound C Alq (10%)  (50Å) (450 Å) Comparative Compound A NPD Compound D Compound C Alq Example1  (7%) (100 Å) (400 Å) Comparative Compound A NPD Compound E Compound CAlq Example 2  (7%) (100 Å) (400 Å) Comparative Compound B NPD CompoundF Compound C Alq Example 3  (8%)  (50 Å) (450 Å) Comparative Compound BNPD Compound G Compound C Alq Example 4  (7%)  (50 Å) (450 Å)Comparative Compound B NPD Compound H Compound C Alq Example 5 (10%) (50 Å) (450 Å) Comparative Compound A NPD Compound I Compound C AlqExample 6 (10%) (100 Å) (400 Å) Comparative Compound A NPD Compound JCompound C Alq Example 7 (10%) (100 Å) (400 Å)

TABLE 2 VTE device results Rela- Rela- tive tive Rela- Initial Rela-λ_(max) Volt- tive Lumi- tive x y (nm) age EQE nance LT80 Example 10.355 0.607 530 1.0 0.9 0.8 1.3 Example 2 0.373 0.599 532 1.1 0.8 0.81.2 Comparative 0.358 0.607 528 1.0 1.0 1.0 1.0 Example 1 Comparative0.342 0.616 526 0.9 0.9 0.9 0.6 Example 2

TABLE 3 VTE device results Rela- Rela- tive tive Rela- Initial Rela-λ_(max) Volt- tive Lumi- tive x y (nm) age EQE nance LT80 Example 30.456 0.533 562 1.0 1.1 1.1 1.6 Example 4 0.478 0.515 566 1.0 1.1 1.12.7 Comparative 0.448 0.540 558 1.0 1.0 1.0 1.0 Example 3 Comparative0.480 0.512 570 1.04 1.0 1.0 2.4 Example 4 Comparative 0.420 0.564 5521.0 1.0 1.0 1.1 Example 5

TABLE 4 VTE device results Rela- Rela- tive tive Rela- Initial Rela-λ_(max) Volt- tive Lumi- tive x y (nm) age EQE nance LT80 Example 50.359 0.609 528 0.9 1.0 0.9 1.4 Example 6 0.350 0.614 528 1.0 1.1 0.91.6 Comparative 0.340 0.622 528 1.0 1.0 1.0 1.0 Example 6 Comparative0.358 0.611 530 1.1 1.1 1.1 1.1 Example 7

Tables 2, 3 and 4 summarize the performance of the devices. The CIEcoordinates, driving voltage (V), and external quantum efficiency (EQE)were measured at 1000 nits, while the lifetime (LT_(80%)) was defined asthe time required for the device to decay to 80% of its initialluminance under a constant current density of 40 mA/cm². Devices withsimilar colors were grouped in different device results tables formeaningful comparison. The benefit of having a deuterated methyl groupon the 5th position of the 2-phenylpyridine ligand can be clearly seenfrom the device data. All the devices with the inventive compoundsshowed similar voltage and EQE, but exhibited extended device lifetimecompared to comparative examples. The inventive compounds not onlyshowed device lifetime advantages over non-deuterated compounds with thesame substitution pattern, but also showed better performance overdeuterated methyl substitution at other positions, such as the 6^(th)position on the pyridine (Compound E and Compound H).

It is understood that the various embodiments described herein are byway of example only, and are not intended to limit the scope of theinvention. For example, many of the materials and structures describedherein may be substituted with other materials and structures withoutdeviating from the spirit of the invention. The present invention asclaimed may therefore include variations from the particular examplesand preferred embodiments described herein, as will be apparent to oneof skill in the art. It is understood that various theories as to whythe invention works are not intended to be limiting.

We claim:
 1. A heteroleptic iridium compound having the formulaIr(L¹)_(n)(L²)_(3-n): wherein the ligand L¹ is a first ligand havingFormula I,

wherein the ligand L² is a second ligand having Formula II,

wherein L¹ is different from L²; wherein R¹ is a partially or fullydeuterated group selected from the group consisting of alkyl andcycloalkyl; wherein R² represents mono, di, tri substitutions or nosubstitution; wherein R³, R⁴, and R⁵ each represent mono, di, tri, tetrasubstitutions or no substitution; wherein R² and R³ are eachindependently selected from the group consisting of hydrogen, deuterium,alkyl, cycloalkyl, and combinations thereof; wherein R⁴ and R⁵ are eachindependently selected from the group consisting of hydrogen, deuterium,halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy,amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl,heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof; wherein at least one of R² and R³ is at least mono-substitutedwith a substituent selected from the group consisting of alkyl,cycloalkyl, combinations thereof, and partially or fully deuteratedvariations thereof; wherein two R⁴ can be joined or fused to form anaromatic ring; wherein the R² para to the N—Ir bond is alkyl,cycloalkyl, a partially or fully deuterated variant thereof, or acombination thereof; and wherein n is 1 or
 2. 2. The compound of claim1, wherein R¹ is a fully deuterated group selected from the groupconsisting of alkyl and cycloalkyl.
 3. The compound of claim 1, whereinR¹ is a fully deuterated group selected from the group consisting ofmethyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl,2-methylpropyl, pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl,1,1-dimethylpropyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl, cyclopentyl,and cyclohexyl.
 4. The compound of claim 1, wherein L¹ is selected fromthe group consisting of:


5. The compound of claim 1, wherein L² is selected from the groupconsisting of:

wherein R^(A), and R^(C) each represent mono, di, tri, tetrasubstitutions or no substitution; wherein R^(B) represents mono, di, trisubstitutions or no substitution; and wherein R^(A), R^(B), and R^(C)are independently selected from the group consisting of hydrogen,deuterium, methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl,2-methylpropyl, pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl,1,1-dimethylpropyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl, cyclopentyl,cyclohexyl, and combinations thereof.
 6. The compound of claim 1,wherein the compound is selected from the group consisting of:


7. The compound of claim 1, wherein L² is selected from the groupconsisting of:

wherein R^(A), and R^(C) each represent mono, di, tri, tetrasubstitutions or no substitution; wherein R^(B) represents mono, di, trisubstitutions or no substitution; and wherein R^(A), R^(B), and R^(C)are independently selected from the group consisting of hydrogen,deuterium, methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl,2-methylpropyl, pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl,1,1-dimethylpropyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl, cyclopentyl,cyclohexyl, and combinations thereof.
 8. The compound of claim 1,wherein R⁴ and R⁵ are not partially or fully deuterated variationsthereof.
 9. The compound of claim 1, wherein at least one R², R³, R⁴, orR⁵ is undeuterated alkyl, undeuterated cycloalkyl, or a combinationthereof.
 10. The compound of claim 1, wherein the R² para to the N—Irbond is alkyl, cycloalkyl, a partially or fully deuterated variantthereof, or a combination thereof.
 11. A first device comprising a firstorganic light emitting device, comprising: an anode; a cathode; and anorganic layer, disposed between the anode and the cathode, comprising acompound having the formula Ir(L¹)_(n)(L²)_(3-n): wherein the ligand L¹is a first ligand having Formula I,

wherein the ligand L² is a second ligand having Formula II,

wherein L¹ is different from L²; wherein R¹ is a partially or fullydeuterated group selected from the group consisting of alkyl andcycloalkyl; wherein R² represents mono, di, tri substitutions or nosubstitution; wherein R³, R⁴, and R⁵ each represent mono, di, tri, tetrasubstitutions or no substitution; wherein R² and R³ are eachindependently selected from the group consisting of hydrogen, deuterium,alkyl, cycloalkyl, and combinations thereof; wherein R⁴ and R⁵ are eachindependently selected from the group consisting of hydrogen, deuterium,halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy,amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl,heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof; wherein at least one of R² and R³ is at least mono-substitutedwith a substituent selected from the group consisting of alkyl,cycloalkyl, combinations thereof, and partially or fully deuteratedvariations thereof; wherein two R⁴ can be joined or fused to form anaromatic ring; wherein the R² para to the N—Ir bond is alkyl,cycloalkyl, a partially or fully deuterated variant thereof, or acombination thereof; and wherein n is 1 or
 2. 12. The first device ofclaim 11, wherein the first device is selected from the group consistingof a consumer product, an organic light-emitting device, and a lightingpanel.
 13. The first device of claim 11, wherein the organic layer is anemissive layer and the compound is an emissive dopant.
 14. The firstdevice of claim 11, wherein the organic layer is an emissive layer andthe compound is a non-emissive dopant.
 15. The first device of claim 11,wherein the organic layer further comprises a host.
 16. The first deviceof claim 15, wherein the host comprises a triphenylene containingbenzo-fused thiophene or benzo-fused furan; wherein any substituent inthe host is an unfused substituent independently selected from the groupconsisting of C_(n)H_(2n+1), OC_(n)H_(2n+1), OAr₁, N(C_(n)H_(2n+1))₂,N(Ar₁)(Ar₂), CH═CH—C_(n)H_(2n+1), C≡C—C_(n)H_(2n+1), Ar₁, Ar₁—Ar₂, andC_(n)H_(2n)—Ar₁; wherein n is from 1 to 10; and wherein Ar₁ and Ar₂ areindependently selected from the group consisting of benzene, biphenyl,naphthalene, triphenylene, carbazole, and heteroaromatic analogsthereof.
 17. The first device of claim 15, wherein the host comprises acompound selected from the group consisting of: carbazole,dibenzothiophene, dibenzofuran, dibenzoselenophene, azacarbazole,aza-dibenzothiophene, aza-dibenzofuran, and aza-dibenzoselenophene. 18.The first device of claim 15, wherein the host is selected from thegroup consisting of:

and combinations thereof.
 19. The first device of claim 15, wherein thehost comprises a metal complex.
 20. A formulation comprising a compoundaccording to claim 1.